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I R. T.'LOZIER. AUTOMATIC CIRCUIT BREAKER FOR MOTORS- No. 492,036.

Patented Feb. 21, 1893.

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Uivrrnn STATES ATEN'T Enron.

ROBERT T. LOZIER, OF NEW? YORK, N. Y., ASSIGNOR TO THE EDISON GENERALELECTRIC COMPANY, OF SAME PLACE.

AUTOMATIC CIRCUIT-BREAKER FOR MOTORS.

SPECIFICATION forming part of Letters Patent No. 492,036, dated February21, 1893.

Application filed April 4, 1892. Serial No. 427,607. (No model.)

To ctZZ whom it may concern:

Be it known that I, RQBERT T. LOZIER, a citizen of the United States,residing in New York city, county and State of New York, have invented acertain new and useful Improvement in Automatic Circuit-Breakers orSwitches for Electric Motors, of which the following is a specification.

The present invention relates to an im proved device for protectingelectric motors under certain abnormal conditions herein afterspecified.

The object of the invention is to automatically open the main circuit ofa motor, should the current for the motor be stopped, or abnormallydiminished.

The armatures of shunt-wound motors are of such low resistance as tomake it necessary, when starting said motors, to temporarily interposein the circuit some form of resistance in series with the armatures,until the latter have reached a speed that will generate. sutiicientcounter-electro-motive force to keep the current passing through thearmatures within the limits of their capacity. This resistance, inpractice, consists of a rheostat, having a sliding contact, by which theoperator successively cuts out of circuit the resistance coils of therheostat as the armature approaches its normal speed, so that when thatpoint is reached the resistance is entirely out out, the armature beingconnected directly across the line. Now, should the speed of the motorbe reduced, or stopped entirely, by an interruption or diminution in thecurrent supplied, unless the resistance is again interposed in thecircuit before the normal current supply is resumed, damage may becaused by the excess of current which will be allowed to pass throughthe motor armature, owing to its lack of counter=electroanotive force.As it is possible that the operator will not be present to readjust thestarting rheostat in the case of an interruption of the current supplyor initial electroqnotive force, I provide a switch which shallautomatically open the main motor circuit when the strength of themotors fieldmagnets has weakened sufficiently to reduce thecounter-electro-motive force of the armature to such a point that theinitial electro-motive force, when resumed, would otherwise transmit anexcess of current through the armature, thus requiring or permitting theoperator to properly adjust the starting rheostat before again puttingthe motor into operation.

In the accompanying drawings, Figure 1 is a diagrammatic view,illustrating the apparatus and the circuit connections preferred; Fig. 2is a similar view of a modified apparatus; and Fig. 3 is a view of theswitch at right angles to the view in Fig. 1.

1 is the supply circuit or wire, from which the motor 2 receives currentfor energizing its field-magnet coil 3 and armature at. One terminal ofthe motor is connected to the resistance conductor 5 at the extremity6', the opposite extremity of the resistance being open, and theresistance being provided with a circular series of contacts 6, withwhich the switch-arm 7 is adapted to make contact successively. Theswitch-arm is connected with the line at the left of the motor, by meansof conductor 8 connected to spring 9 bearing on the hub of said arm. Thelong contact 10, which is entirely disconnected from the resistance, isconnected by wire ll to one of the contacts, 12, of the circuit-breaker,there being preferably three other contacts 12, 12", 12', the two former(12, 12") being connected together and the latter being connected to aterminal of the motor.

13 is an armature, supported by a rod 14, having a spring lat tending tomaintain the armature away from the magnet pole N,which pole is one ofthe field-magnet poles, but in the figureisshown disconnected from themotor for the purpose of showing the same on a larger scale than couldotherwise be done and to avoid confusion of lines.

The body on which the switch is mounted is marked N to indicate that itis the same as the pole N of the motor.

To the upper end of the rod M are connected two arms 15, which are inturn pivoted at 16 and which carry springs or arms 17 adapted, whenmoved forward, to connect the contacts 12, 12 and 12", 12 of thecircuitmaker and breaker, the contacts being side by side, in pairs, asshown in Fig. 3. By arranging the contacts of the circuit-breaker asdescribed, the circuit is made and broken simultaneously at two points(12, 12 and 12",

12'), an excellent contact between the fixed and movable contacts isobtained, and said movable contacts are given a long throw, so that alldanger of arcing is avoided. On the pole piece N are secured twonon-magnetic standards 18, having central slots within which pins 19,projecting from the armature, are adapted to slide. The standards carryanonmagneticcross-piece 20, havingstandards 21 and being perforated forthe passage of the rod 1%. The spring 14: presses on the top of thiscross-piece at its lowerend, and its upper end against the adjustablenut The two arms l5 are slotted at their ends, and a pin 23 passesthrough both at the point where they cross. The armature being mountedin the guide-way as described, is normally held in its upper position bythe spring 1%, but is free to move downward when the pole N exerts therequired attraction.

The switch-arm 7, when the motoris out of use stands between the contact10 and the open end of the resistance conductor. To start the motor saidarm is moved in the direction of the arrow. This puts all the resistance(which is large in relation to the armature) in series with the motor,reducing the current in the armature circuit to within the capacity forwhich the motor and its circuit have been designed. This current, however, is suflicient to energize the field-magnets so that they willattract armature 13, closing the circuit at the circuit-breaker, so thatwhen the switch-arm moves onto contact 10 the circuit will be from lineto the switch-arm, to contact lO, wire 11, through the contacts of thecircuit-breaker, to the positive terminal of the motor, and through themotor to line. IVith this arrangement, the entire current which passesto the motor must pass through the circuit-breaker. As the switch-armapproaches contact 10 the armature gains in speed and resultantelectro-motive force. If, now, the current on the line falls or ceases,the spring ll immediately raises the armature and opens the circuit.\Vhen the current is resumed, the motor will not start, because itscircuit is open, but when the arm '7 is moved forward onto theresistance contacts, the motor at once starts, and as the arm is movedaround the circuit-maker is again operated, as already described.

In the modified arrangementshown in Fig. 2, the parts are numbered, asfar as convenient, to correspond with Fig. 1. In this arrangement, thereis but one path for the current between the resistance switch orcontrolling device and the positive terminal of the motor, and this pathis composed of the wire 11, extending to the contacts 12, 12 of thecircuit-breaker, said contacts being adapted to be connected by theplate 17 carried by the pivoted arm 15 having acounter-balance weight wand being connected to the armatures 13, 13 by a rod 14:. Instead of onelarge armature, as shown in Fig. 1,I.employ, in this form, twoarmatures, which may be round and adapted to slide in socketsson thefieldmagnet pole. The long contact 10 of the resistance switch is, inthis case, connected to the end of the resistance conductor at 6.

IVhen it is desired to start the motor, it is necessary to close thecircuit at 12, 12 by hand. As the switch-arm is moved around, thecircuit is first closed through all the reresistance, and then theresistance gradually removed, the field-m agnet soon attainingsufficient power to hold the circuit closed at the circuit-breaker.Should the current on the line fall or cease, the main line would be atonce opened, as already described.

By having the circuit-breaker exterlor to the terminals of the motor, itis clear that the latter will not automatically start up on a resumptionof the normal current, as would be the case, for example, if thecircuit-breaker were in the armature branch of the motor, as has beenheretofore proposed. In many cases, it is desirable, when the motor hasbeen arrested, that it should only start when the operator starts itintentionally, and such action is necessary with the arrangement ofappatus described.

While I prefer to have the circuit-breaker entirely outside of the motorterminals, that is, outside of the points where the field-magnet andarmature branches unite, when a shunt motor is used, it will be evidentthat some of the features described will be equally applicable when thecircuit-breaker is 111 the armature branch.

\Vhat I claim is- 1. The combination of a motor, a circuitbreaker in themain motor circuit, means, such, for example, as a spring, tending tomove the same to its open position, and an armature in operativerelation to the fieldmagnet of the motor connected tosaidcircuit-breaker so as to close the circuit when the armature isattracted, substantially as described.

2. The combination of a shunt motor, a circuit-breaker in the main motorcircuit out side of the motor terminals, means, such, for example, as aspring, tending to move the same to its open position, and an armature,in operative relation to the field-magnet of the motor, connected tosaid circuit-breaker so as to close the circuit when the armature isattracted, substantially as described.

3. The combination of a motor, arheostatic controlling switch therefor,said switch having considerable resistance in circuit when first movedto close the motor circuit, and being constructed to cut out resistanceas the switch is moved forward,a contact connected to a circuit-breakercontact and through the same to one terminal of the motor, said firstmentioned contact being connected to the line when the resistance is cutout, and a circuitbreaking device having a tendency to open but beingheld closed by the current when it is of normal strength, substantiallyas described.

4i. The combination of a circuit, a rheostatic controlling switch, and amotor interposed in said circuit, a circuit-breaker exterior to themotor terminals and having a tendency to move to its open position, andan armature connected to said circuit-breaker and in position to beattracted by the field-magnet of the motor, substantially as described.

5. The combination of acircuit, a rheostatic controlling switch and amotor interposed in said circuit, said switch consisting of a series ofcontacts connected by resistances, one end of the resistance beingconnected to one terminal of the motor, a switch-arm to which thecircuit is connected, adapted to move over said contacts, beginning atthe end opposite to that connected to the motor terminal,acircuit-breaker held open when the motor is out of use, and an armaturein proximity to the '7 The combination of the field-magn et pole, 3 5

slotted standards 18 carrying a cross-piece and standards, the contactscarried by the latter standards, the reciprocating armature and itssupporting rod, the rods slotted at their adjacent ends and connected tothe armature rod, and the contacts carried by said pivoted arms andadapted to connect the first mentioned contacts, substantially asdescribed.

8. The combination of the movable armature, a rod projecting therefrom,two pivoted arms with slotted intersecting ends, a pin connecting therod with the arms at their intersection, connecting plates carried bythe arms, and contacts adapted to be connected thereby, substantially asdescribed.

9. The combination of a motor, a circuitbreaker in the main motorcircuit having several contacts, means tending to move thecircuit-breaker to its open position, an armature attracted to itsforward position when the current through the motor is of normalstrength, and a circuit-closin g device moved by said armature andconnecting said several contacts, whereby the circuit is broken atseveral points, substantially as described.

This specification signed and witnessed this th day of March, 1892.

ROBERT T. LOZIER.

Witnesses:

CHARLES M. OATLIN, GEORGE E. BUCHANAN.

